Conventional modern combines usually have a pair of substantially flat, perforated sieve plates. The harvested grain is deposited on the upper sieve plate, and a fan directs air upwardly and rearwardly through this plate to blow away the chaff and foreign material and to permit the clean grain to fall through the perforations of the plate. Normally, a second sieve plate is located below and in spaced relation to the first sieve plate where the same action is repeated.
A problem associated with the flat sieve plates is that when the combine operates on a lateral incline, the sieve plates are also inclined such that grain moves to one lateral side thereof and spills therefrom. Also, the conventional sieve plates must be cleaned regularly during operation of the combine, and as frequently as every two hours.
Therefore, a primary objective of the present invention is the provision of an improved sieve plate which reduces grain loss during operation of the combine on uneven terrain.
Another objective of the present invention is the provision of a sieve plate which requires less frequent cleaning than conventional sieve plates.
A further objective of the present invention is the provision of a sieve plate which permits the combine to be operated at increased speeds during harvesting.
A still further objective of the present invention is the provision of a sieve plate for grain combines which is economical to manufacture, and durable and efficient in use.
A still further object of the invention is to provide a seive plate that will provide a substantially horizontal cleaning portion even when the combine is laterally inclined.
These and other objectives will be apparent to those skilled in the art.